North Americans should try to get at least an hour of moderate exercise such as brisk walking every day, the Institute of Medicine panel recommended -- doubling the surgeon-general's 1996 target of half an hour.

"We recognize that lifestyles of many in the United States and Canada might make this goal seem difficult to achieve," panel chair Joanne Lupton, a professor of nutrition at Texas A&M University, told a briefing.

"As difficult as it may be, if we are aiming at eliminating the major killers of today we will have to increase physical activity," Dr. Benjamin Caballero, director of human nutrition at the Johns Hopkins University school of public health, said.

The panel of 21 scientists and physicians, formed at the request of Congress and various U.S. government agencies and Health Canada, stressed that the guidelines are aimed at healthy people and not designed to help people lose weight.

But the experts also noted that more than half the U.S. population is overweight, which increases the risk of heart disease, diabetes and some cancers.

Panel member George Brooks, a professor of integrative biology at the University of California Berkeley, said people should try to balance caloric intake with physical activity. The report gives details of how many calories a person should eat based on weight and activity.

EAT ACCORDING TO EXERCISE LEVELS

"Instead of recommendations based on age, height and weight alone, we're basically saying, 'You tell me what exercise you do, and I'll tell you what you can eat,"' Brooks said in a statement.

The guidelines also do not offer any specific advice on which foods to eat but give Americans a range of nutrients to aim for in their diets. They also do not mention the benefits or drawbacks of any weight-loss diet and panel members declined to comment on any such diets.

"To reduce the risk of chronic illness, we recommend that adults get 45 to 65 percent of their calories from carbohydrates and 20 to 35 percent of their calories in the form of fat," Lupton said.

"We suggest that no more than 25 percent of total calories should come from added sugars -- essentially soft drinks, pastries, cookies, candy and other foods and beverages to which sugar is added during production."

Only 10 to 35 percent of calories should come from protein, the panel said -- and it said there is no evidence to show that protein supplements are needed by any healthy person, including bodybuilders.

Some fat is needed for health and the group set, for the first time, recommended intakes of essential fatty acids. These include the omega-3 and omega-6 fatty acids found in vegetable oils and also in some fish.

Last month the same panel issued advice on saturated fats found in milk and meat products and the trans-fatty acids found in hardened, or hydrogenated, oils and margarine. It said people do not need any in their diet and should aim for zero -- but also noted this would be almost impossible to achieve.

Based on this, the U.S. Food and Drug Administration plans to issue new rules requiring that foods carry information on trans-fat content to their labels.

The panel also set guidelines for fiber of 38 grams a day for a man and 25 for a woman -- less for over-50s who in general eat less.

The full report is available on the Internet at http:/ www.nap.edu.

(Xinhua News Agency September 7, 2002)